Lap



Aug. 19, 1930. R. GRoE'rcHEN LAP Filed Jan. 29, 1927 ,m Ca W wm ,w ma Y k [QJ mp Patented Aug. 19, 1930 PATENT w oFFlcE BICEABD GBOETCHEN, OF CHICAGO, ILLNOIS Application lled'l'anuary 29, 1927. Serial No. 184,452.

This invention relates to a smoothing, lapping or polishing process and to an ap ratus for carrying out such process. It

for one object to provide a lap, the major portion of which is permanent and in which the part subjected to abrasion and wear is removable. Another object is to provide a lap which will automatically accommodate itself in lapping to holes of a relatively wide Variation in size. Another object is to provide a process whereby a constantly moving and shifting layer of abrasive is brought up to carry out the la ping operation.

' Other objects will appear rom time to time throughout the specification and claims.

The invention is illustrated more or less diagrammatically in the accompanying drawings, wherein: I

Figure 1 is a Vertical cross-section of a piece durin the lapping operation showing the lap an associated parts in elevation.

F igure 2 is a perspective view of the permanent portion of the lapping device with the wearing removed.

Figure 3 is a perspective of the wearing part of the lap.

Figure 4 is a trafinsverse cross-section taken on line 4-`-4 of Fi'gre 1 and on an enlarged scale.

Figure 5 is a view similar to Figure 4 in which the wearing part has been reversed in relation to the permanent part of the lap. F igure 6 is a view similar to Figure 3,

showing a modified form of the wearingV member.

Like parts are indicated by like characters throughout.

A is a piece in which a perforation A1 has w been formed.

B is any suitable rotating device in which the lap C is removably positioned.

The lap consists of a main shank portion C which may have a reduced upper end C1 and which normally has formed about it an outwardly extending flan e or ring C2. It is provided in its outer or ower end with a slot. C3, and preferably at the inner end of the slot it has an venlargement C1.

D is a softer wearing member or part formed in a generally cyhndrical shape, provided with an inwardly bent flange or'ed e D1 which is. circular. with the axis of te member D. The member D is preferably so proportioned that when it is positioned upon the outer or lower end of the lap C with the tongue or flange D1 lying within the slot C3, its free edge will not meet the point X at which the flange D1 is inwardly turned and there is thus left a narrow slot or groove like portion X1. When the tool is in use, an abrasive or preferably a lubricant is applied to'it, being inserted into the slot and this works down into the space X1 and forms a Vertical strip of abrasive material extending throughout-the length of the member D. In the modified form shown in Figure 6, a wearing element is used in which the abrasive material forms a part of the wearing element and thus in effect, the wearing element is impregnated with abrasive and formsuin itself an abrasive elementV` This element may be used with or without additional abrasive. A

Although I have shown an operative device, still it will be obvious that many changes might be made in size, shape and arran ement of parts without departing materially from the spirit of my invention; and I wish, therefore, that my showing be taken as in a sense diagrammatic.

For normal conditions the shank member C may be of steel and the wearing member vD of a softer material. For one purpose it may be made of copper.

The use and operation of the invention is as follows: w

When it is desired to smooth or lap the interior of a circularopeninz, a tool such as that shown, of suitable size is provided and the wearing part is positioned about it. This composite part is then inserted in the hole to be treated. A lubricant is applied, being most conveniently inserted through the enlargement at the'inner end ofthe slot and with this abrasive preferably in the form of powder, is normally also applied although either may be used alone. The lap is then set in rotation and the materials work down- Ward along the slot and outward into the area X1 and form an axially'extending abrasive strip or zone which carries out the lappin effect as the part is rotated. Under norma conditions rotation is in the direction of the arrow shown in Fi 4. Where the tool is somewhat too small for the hole or for other .reas0ns, it is sometimes desirable to reverse'the rotation of the rt. When the part is rotated in the direction of the arrow the rotation tends to cause the free edge of the member D to approach` the edge' X. When the rotation is in the reverse direction, it tends to force the free edge of the'member 'D away from the edge X and thus in eflect, to swell or enlarge the size of the wearin element and so to carry out more complete y the la ping efl'ect. During these o rations, the abIi-asive normall finds its way It all parts of the exterior of t e weari element D but it is collected in the greatest quantity in the -aone X1.

ici'nim :1 a a appmg evice, a constituting a mandrel, a flexible metallic sleeve, having a flange thereon, constitutin an Operating member removabl mounte thereon, said driving member having a pasi sage formed therein, said flange anchored in the passage whereby the sleeve is attached to the driving member, said sleeve extending about the driving mandrel throughout the meor portion of the periphery thereof, one en of the sleeve being free to permit relative ;'movement thereof with reference to the mandrel. a

2. In a lapping device, a driving -member constituting a mandrel, a flexible metallie sleeve, constituting an Operating member removably mounted on the mandrel, the sleeve and mandrel being formed with interfitting parts preventing relative rotation of the sleeve and mandrel, said sleeve extending about the driving mandrel throughout the major portion thereof. one end of the sleeve being free to permit relative movement thereof with reference to the mandrel.

3. In a lapping device, a driving member constituting a mandrel, a split metallic sleeve, constituting an operatin member, removabl' mounted thereon, said sleeve and mandre being` formed with interfitting parts preventing relative rotation of the sleeve and mandrel, said sleeve embracing the mandrel circumferentially, with the opposite ends of the split sleeve terminatin m spaced relation, one end of said sleeve ing free to permit relative movement thereof with reference to the mandrel.

4. In a lapping device, a driving member eonstituting a mandrel, a split metallic sleeve constituting an Operating member, removably mounted thereon, cooperative means formed on the sleeve and mandrel for securing one end of the sleeve against movement circumferentially of the mandrel, said sleeve embracing the mandrel circumferentially driving member' more closely and when rotate in the opposite direction to tend to move outwardly away from the mandrel to expand the sleeve.

Signed at Chicago, count of Cook, and State of Illinois, this 27th ay of January,

t RICHARD GROE'ICHEN.

I apping device is -rotated in one direction to hu the mandrel 

